Brake



A ril 23, 1935. w. H. DELAHAYE BRAKE Filed Dec. 2, 1929 INVENTOQ: WALTEQ' H. DELAHAYE.

ATTORNEY Patented Apr. 23, 1935 BRAKE Walter H. Delahaye, Ottawa, Ontario, Canada, assignor to Bendix Brake Company, South Bend, Ind.

Application December 2, 1929, Serial No. 410,941

20 Claims.

This invention relates to automobile brakes and has for object to provide a novel construction of servo or self-energizing brake in which the servo action is developed by a sliding shoe 5 carried on one of the main shoes which is formed to provide a guide for the servo shoe.

A novel feature in the construction is the method of mounting the servo shoe and the means provided to secure proper lubrication between the sliding surfaces of the supporting shoe and the servo shoe.

Another object is to provide a servo brake which is not entirely dependent on the servo action but which develops a braking pressure when the wheels are at rest, or when the servo shoe is incapacitated through accident or some unforeseen cause.

The invention consists in the construction, combination and arrangement of parts hereinafter described and more particularly pointed out in the appended claims.

Referring now to the accompanying drawing, which illustrates, by way of example, several embodiments of the invention:

Figure 1 shows an elevation of one embodiment;

Figures 2, 3 and 4 are fragmentary elevations of three modifications;

Figure 5 is a section through the servo shoe along the section line 5-5 of Figure 1;

Figure 6 is a similar section taken along the line 6-5 of Figure 4.

Referring to the drawing and particularly to Figures 1 and 5, within the drum I shoes of well known type 2 and 3 are mounted on a fixed pivot 4. The shoe 2 has a flat cam-engag g surface 5 at its free end and on the opposing free end of the shoe 3 is pivotally mounted on a pivot 8 a lever I, which has rounded projections 8 and 9 at its inner and outer extremities adapted to engage the surface 5. The outer end of the lever 1 is pivotally attached at I to one end of a servo shoe l which is slidably mounted on the shoe 3. Both the shoes 2 and 3 are of the flanged type and the flange of the shoe 3 is offset inwardly at II to provide a guiding surface for the servo brake which is mounted thereon as shown in Figure 5. The brake may be applied by means of a rockshaft I2 provided with an arm I3 carrying a roller H. The rockshaft l2 may be operated by the usual lever 15. which is connected to the brake rod "i. As shown in Figure 1 the brake is designed to give a servo action when the wheel is revolving in either direction. It will be apparent that when the shoe 3 is forced against the drum by the roller ll through operation of lever I the servo shoe III will be caused to slide on the surface II and in so doing the lever 'l is rocked on its pivot 6, pressing the projection I or projection 9 of the lever against the surface 5 of the shoe 2 according to the direction of rotation, thus causing the shoe 2 to engage the drum I with a force that is proportionate to the drag developed by the servo shoe.

In Figure 5 the shoe 3 is shown as being formed from two angular sections I1 and I8 placed back to back, this being quite a common construction. The servo shoe supports a lining l9. To maintain the servo shoe in position on flanges II it is provided with flanges 28 to engage the under side of the flanges H. As it is necessary that the servo shoe should slide freely on the main shoe, lubrication is provided by means of inserts of graphite or other dry lubricant which may be variously placed and in the drawing is indicated by the inserts 2|.

In the modification shown in Figure 2, the means for applying the initial pressure have been changed. In this form the levers l and I5 are both flxed to the pivot 6 which is extended through a clearance hole in the brake support to allow this. Operation of the lever 14 will cause movement of the lever I as above described.

In the modification shown in Figure 3 a point 22 on the shoe 2 is connected to the pivot point I of the servo shoe 9 by a toggle 23 and this is operated from the levers l3 and I5 by means of a link 24. It will be seen that this operates in the same manner as the above described forms. There is, however, no reverse servo action in Figures 2 and 3, though they could be readily modified to have such action.

In the form shown in Figures 4 and 6, the shoe 2 is directly operated by a cam 25. On the free end of shoe 3 a lever 26 is mounted on a pivot 21. This lever 25 presents a cam-engaging surface 28 between which and the end of the shoe 2 the cam 25 is arranged to operate, the shoe 2 being provided with an appropriate cam-engaging surface 29. The servo shoe I0 is provided with depending arms 30 which are connected to the lever 26 by means of the link 3!. The servo shoe It! may be provided with the lubricating plugs 32 as in the other forms. It will be seen that in this form, when the cam 25 is rotated an initial application of the brake is obtained and this initiates the movement of theservo shoe III as in the other forms previously described. The movement of the servo shoe in this case causes a pull to be exerted on the lever 26 because of the connection 3|. This pull causes the lever 26 to 55 pivot on the cam and exert an effort on the pivot 21 in a direction to apply the brake.

The drawing shows'brake shoes of certain section and a servo shoe formed thereon but the shape of both the servo shoe and the main shoe and the method of mounting the one on the other is immaterial and must not be regarded as being restricted to the type shown. It is the intention to cover all forms of the device which may rightly be regarded as falling within the scope of the appended claims.

What I claim is:

1. In a servo brake, the combination of a pair of friction shoes positioned on a support, a servo shoe mounted on one end of one of said shoes and means directly connected thereto for exerting a servo action on the first mentioned shoes together with driver-operated applying means acting on at least one of said pair of shoes independently of the servo shoe.

2. In a brake as claimed in claim 1, one of said pair of shoes having a guiding surface for a relatively short distance from one end, and a friction surface, said servo shoe being mounted for movement on said guiding surface.

3. In a brake, a plurality of pivoted shoes, one of the pivoted shoes having a friction surface along a portion of its circumference and an arcuate guiding surface on the remainder of its peripheral face, a servo shoe mounted to slide on said guiding surface, a lever pivoted to the free end of the shoe, said lever being connected to the servo shoe.

4. In a servo brake, the combination with a support and a pair of shoes pivoted thereon, an applying device acting on one of said shoes intermediate its ends, means operating to expand the free ends of the shoes, a servo shoe mounted to slide on one of said pivoted shoes, a lever also pivoted to said shoe, the free end of the lever engaging the free end of the other shoe and exerting an expanding force thereupon when movement of the servo shoe relative to the supporting shoe takes place.

5. In a brake, a supporting shoe and a sliding servo shoe mounted thereon, the peripheral face of the supporting shoe having a portion carrying a friction facing and at its free end a depressed unfaced portion, said depressed portion forming a guiding surface for said sliding servo shoe.

6. In a brake shoe, a rim having for a short distance at one end an offset portion, a friction facing on the rim for the remainder of its length, and a servo shoe mounted to slide on the offset portion, in combination with a lever mounted on the brake shoe and operated by said servo shoe.

' 7. In a brake shoe, a curved support, said support having a curved outer face, a friction facing secured to a portion of the curved face for the greater part of its length, the remaining portion of the length of said face being of a smaller radius but concentric with the first mentioned portion, a servo shoe mounted to slide on said remaining portion, a friction surface on the servo shoe and a lever pivoted to the adjacent ends of the support and servo shoe.

8. In a brake shoe as set forth in claim 7, said servo shoe having guiding portions engaging opposite side edges of said support.

9. In a brake shoe as set forth in claim 7, said support having a curved outer surface, a portion of said surface being curved on a smaller radius, a second support having an inner bearing surface to ride on the surface of smaller radius, retaining means on said second support to engage around the first support, and means to lubricate bearing surfaces of the-supports.

10. In a brake shoe of the class described,-a support, said support presenting a flanged periphery, said flanges presenting a curved outer surface to carry a friction surface and-a servo shoe, the part carrying the servo shoe being of less radius, said servo shoe being formed with a support having a curvature complementary to the curvature of lesser radius and engaging thereon, guiding flanges depending from the last mentioned support lying adjacent the first mentioned flanges, inwardly turned retaining flanges on said guiding flanges and means carried by some of said flanges to lubricate the engaging surfaces of the support.

11. In a brake shoe as set forth in claim 10,

said lubricating means comprising inserts of compressed lubricant carried by certain of the flangesand presenting lubricating material to the sliding surfaces.

12. In' a brake shoe as claimed in claim 10, said support having means for pivoting it to a stationary support adiacent that extremity carrying the friction surface, means for pivoting a lever at the opposite end .and means for connecting the lever to the support of the servo shoe.

13. In a brake of the class described, a support, a pair of brake shoes having two adjacent ends pivoted to the said support, a lever pivoted on the free end of one of the shoes and engaging the free end of the other shoe, means to operate the lever,- a servo shoe, means to connect the servo shoe to the lever so as to. transmit the servo effort thereto, said servo shoe being moimted on the shoe carrying said lever.

14. In a brake as set forth in claim 13, said lever being pivoted at its outer end to the servo shoe and at a point intermediate its ends on the shoe carrying the same, its free end being provided with at least one offset portion adapted to engage the free end of the other shoe.

15. A brake comprising friction elements having separable ends, a servo shoe movable along one of the ends and acting to spread said ends and means for applying at least one of the friction elements in addition to the servo shoe.

16. A brake comprising friction means having separable ends, a servo shoe movable along one of the ends and actingto spread said ends and means for applying at least part of the friction means and simultaneously actuating the servo shoe by forcing said one end into applied position.

17. A brake shoe having a servo shoe independently movable bodily along the brake shoe at one end thereof, and a lever pivoted on the brake shoe and connected to said end of the servo shoe.

18. A brake shoe having a servo shoe independently movable thereon, a lever pivoted on the brake shoe and pivoted to said servo shoe, and a driver-operated applying device acting directly on said brake shoe and acting indirectly on the servo shoe through the medium of the brake shoe.

19. A brake comprising -a pair of anchored shoes, one of which has a short servo shoe mounted thereon at the end adjacent the other shoe, an applying device therefor, and an auxiliary applying device carried by one 'shoe and acting on 

